1. Field of the Invention
An inorganic powder uses a UV solid light source. The chemical formula of main component is Me+21-xLn+32-ySi2O8:TR+2x:TR+3y. When the indium gallium nitride and gallium nitride-based allomorphous semiconductor short wave UV light is being used under conditions of excitement, multiple band white light can be obtained.
2. Description of Related Art
In recent years, the manufacturing technology of the solid light source has improved continuously. The efficiency of illumination is greatly increased. Since the solid light source may emit nearly monochrome light, and is highly reliable, enjoys longevity, and can be broadly applied, it has been used in many lighting equipment applications. There is a trend of replacing traditional vacuum light bulbs with solid light sources.
A white light source is mixed from multiple colors of light. The white light that can be observed by human eyes contains a mixture of light with at least two or more wavelengths. When human eyes are simultaneously excited by red, blue and green light, or simultaneously excited by the cross compensation light of blue and yellow light, the light is perceived as white light. This principle can be used to generate a solid light source for the white light.
There are main four conventional means of white solid light source generation. The first method uses three solid light sources using InGaAlP, GaN and GaN as materials. The electric current passes, under respective control, through the solid light sources and emits red, green and blue light. Then, a lens is used to mix the light emitted to generate white light.
The second method uses two solid light sources with GaN and GaP as materials. The current passing through these solid light sources is also individually controlled to emit blue and yellow-green light to generate white light. Although the efficiency of illumination for the above mentioned two methods may reach 20 lm/W, if one of the different color solid light sources fails, normal white light cannot be obtained. Additionally, the positive bias is different. Thus, many sets of control electric circuits are required. The cost is high. These are many disadvantages of practical applications.
The third method was developed in 1996 by Nichia Chemical of Japan. An indium gallium nitride blue solid light source and a yellow light-emitting yttrium aluminum garnet fluorescent material are used to form a white light source. Although, at the present time, the efficiency of illumination (as high as 15 lm/W) is lower than those the prior two methods, only one solid light source chip set is required. The manufacturing cost is reduced significantly. Furthermore, the formulation and production technology for the fluorescent material is mature, and commercial products are available.
However, methods two and three utilize a color compensation principle to generate white light. The continuity of spectrum wavelength distribution is not as good as sunlight. After the mixture of the colored light, in the visible light spectrum range (400 nm-700 nm), the color is not even. The saturation of color is low. This phenomenon can be ignored by human eyes, because they only perceive white light. However, high precision optical detectors, such as a video camera or camera, perceive the color rendering as low. Errors will be caused during reduction. Thus, the white light sources generated by these methods can only be used for simple lighting applications.
The fourth white light generating method was developed by Sumitomo Electric Industries, Ltd of Japan. It uses ZnSe material as the white solid light. A CdZnSe thin film is first formed on the ZnSe single crystal baseboard. After energizing, the thin film emits blue light. At the same time, a portion of the blue light shines on the baseboard and emits a yellow light. Finally, the blue and yellow light compensate each other and generate white light. This method utilizes only a solid light source crystal. The operation voltage is only 2.7V, lower than the 3.5V required for a GaN solid light source. Additionally, its generation of white light does not require fluorescent material. However, the disadvantages are that the efficiency of illumination is only 8 lm/W, and the service life is only 8000 hours.
In addition to the aforesaid white light generation methods by a solid light source, according to the prior art there is controlled exciting of Y3Al5O12, a co-fluorescent material wave spectrum attempt. The additives used to replace Al are Ga or Sc. Alternatively, Lu, Tb, and Sm are used to replace Y to achieve limited results. However, these fluorescent material radiation light spectrum are normally located in the green-yellow zone of visible light. It cannot integrate the design of solid light source and the soft white light generated by white lamp with equivalent color temperature of T=2800K-3500K.
In the current art method announced by J. K. Park, the white solid light source uses Ga—N as a base, and its cold light properties. (“White Light-emitting Diodes of Ga—N-Based Sr2SiO4:Eu and the Luminescent Properties” J. Electrochem. Solid State Lett., vol 5 {2002} p. H11). The chemical composition used is silicate inorganic powder based on strontium compounds and with the chemical formula as Sr2-xEu+2xSiO4, wherein x can be 0.1, 0.05, 0.03, or 0.005 shown in the disclosure of “White Light-emitting Diodes of Ga—N-Based Sr2SiO4:Eu and the Luminescent Properties.” The principle of illumination of inorganic powders is related to the transfer radiation of Eu+2 replacement of Sr+2 ions at the crystal sieve anode nodes. The limited utilization of n-silicate inorganic powder production of standard blue light In—Ga—N allomorphous in a white solid light source is that the short wave wavelength used for self-excitement is around λ≦420 nm, where λ=395 nm, λ=405 nm, and λ=380 nm are used.
Although after the aforesaid n-silicate inorganic powder Sr2-xEu+2xSiO4 (x can be 0.1, 0.05, 0.03, or 0.005) is excited by the UV light, the radiation light spectrum is yellow-green, and cold color-adjusted white light can be obtained. Compared to the production equipment of present art used yttrium aluminum garnet fluorescent material, it has much higher Rendering index. It offers the main advantages of the n-silicate inorganic powder solid light source. However, obtaining this advantage can only be achieved when double portions of inorganic powder mixing agents are used in the solid light source.
In addition to the above-mentioned disadvantages that double portions of inorganic powder mixing agents must be used, the strontium europium based n-silicate material has a very low efficiency. When the angles used for the produced white light diodes Sr2-xEu+2xSiO4 (x can be 0.1, 0.05, 0.03, or 0.005) are between 30° and 120°, the light intensity is J=0.1-0.3 candlelight. At the same time, the temperatures of this diode should not exceed 80-90° C. That is, when a solid light source is heated to these values, the light brightness is reduced by half. In addition, the temperatures used in the generation process of the inorganic powder are T=1100-1200° C. This is not sufficient to combine the quantum effect of the inorganic powders. During the synthesizing of various known silicate inorganic powder, the vitrification of products is easily occurs. This forces the grinding of the vitrified inorganic powder and leads to lower quantum effect.
For the present art that uses UV light as solid light source chips, such as U.S. Pat. No. 6,765,237 “White light-emitting device based on UV solid light source and phosphor blend”, a fluorescent body is provided that is the combination of two chemical components, to achieve the UV light excited white light solid light source.